Newbie to the SuperDuty. How does the ESOF locking hubs work in Auto mode?

Newbie to the SuperDuty. How does the ESOF locking hubs work in Auto mode?

I took apart, cleaned and lubed my hubs according to Guzzle’s web page. Thank You Guzzle. My question is: how does the vacuum make the gears work?

Does the vacuum force (suck) the nylon assembly to push the outer gear towards the center of the truck, sliding on the inner gear thus engaging the teeth so that the axle shaft turns the hub?

When the vacuum is gone, does spring pressure pushes the outer gear away from the center of the truck thus disengaging the teeth from the inner gear and allowing the hub to free wheel?

Is this vacuum source constant during 4wd and not present during 2wd or do I not understand how the system works? I have read about a “vacuum pulse” that locks the hubs and another pulse that unlocks the hubs and this confuses me. Could someone please explain?

BTW, I like the way the Auto lock works. I had a set of Warn Auto Lock hubs on my 78 CJ. They worked on the principle of a set of roller bearings that would lock (pinch) when there was torque coming from the drive shaft. There was no vacuum involved at all. The down side was that when you coasted, the front hubs would be in two wheel drive and so you would not get the engine braking on all 4 wheels. These ESOF seem to have solved this problem.

Oh, I should probably tell you that I just purchased my 04 F250 SuperDuty 4x4 with the 6.0 diesel, just had it a week. It has been 18 years since I owned a 4x4. Before this I owned an 87 F250 2wd with the 6.9 diesel. I have found everyone on this site to be a great help.

Is the 40 second vacuum pulse a onetime shot only? Would not he inside of the hub loose its vacuum as you drive or is that why members are replacing the seals inside their knuckles, so that the system does not unlock the front hubs because of a vacuum leak? I know that there is pressure on the gears so that the spring will not unlock the hubs, but what about when you are coasting, does the vacuum get recharged once in a while?

Then can I assume that the second pulse for 20 seconds at a lower vacuum is almost the same as equalizing the pressure inside and outside the hub so that the spring can take over and disengage the hub when there is no pressure meshing the gears.

I am glad I came across this thread. Excuse my thread hy-jack I too am having problems with my 03 superduty esof hubs. I know my evac pump is working properly. It pulls approx 15-18" of vacuum. The canister holds the vacuum also. I noticed that I am going to have top replace some of the tubing/fittings on mine because the vacuum is no-where near 10" near the hubs.

That said, I have a stand alone vacuum pump. I noticed that when I pull a 10-12" vacuum on the hub, it makes the axle shaft harder to turn, but it still does not lock in. Both of my hubs are this way. Manual works fine, but auto does not.

Pulled the hub assmebly out and verified it was lubed and cleaned. What am I missing??

Thread -unjacked. All in an effort to educate us about vacuum actuated hubs.

Glad you are along for the ride. I cleaned both my hubs I still can't get my hubs to unlock the axle shafts in auto. Orderd a vacuum pump but have not picked it up yet. One thought that I have is that the grease I used is too heavy. I am thinking of using CV joint grease in the hubs. Any other opinions? I am also going to take off both hubs and see if the axle shaft still turns.

I read either here or on one of the other sites that there was a TSB suggesting cutting the plastic ring in 3 to 4 spots for the vacuum to get by and effect the diaphragm? Not a whole lot of info though. Might be because too much grease got in the way and the vacuum pump and motion did not move in time??

4mil, took the hubs apart again today, cleaned and lubed with ATF. I did notice that one hub locks and autos properly in my hand, but the other one does not. Apparently, underneath the diaphram, when you turn from auto to lock a piece (I asume plastic) moves up and down. Moves inboard for lock and outboard for auto. This piece underneath the diaphram binds and does not move outboard enough to unlock the drive shaft and so stays locked permanently. So what I did is pushed this piece of plastic under the diaphram outboard in unlock by hand, and assemble the hub without turning the **** to lock so that my front axle free wheels. I have not tested it yet, but I am going to leave my hubs in auto and see if 4x4 locks and unlocks the hubs in auto and if so leave the **** alone. If anyone knows how to fix the **** moving the plastic piece up and down let me know. Next step see if the vacuum works.

I read either here or on one of the other sites that there was a TSB suggesting cutting the plastic ring in 3 to 4 spots for the vacuum to get by and effect the diaphragm? Not a whole lot of info though. Might be because too much grease got in the way and the vacuum pump and motion did not move in time??

Maybe someone else has heard of this?

Was thinking about this the other day.

If you look at the **** of the ESOF hub, there is a white strip, which is actually a filter/breather. No need to drill holes?

Has anyone sucessfully removed the dial and replaced it again without ruining the hub? I will probably try to find one at the wreckers before I tear one apart. Does anyone know if the newer style, the one with the three screws at the dial will fit the older front axles? I am assuming that the ones with the screws around the dial are rebuildable. Since my wife drives the truck a lot, I still want to preserve the auto hubs and besides I think they are neat. Too bad they weren't more service friendly.

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